Linear actuator assemblies are widely used in a variety of applications ranging from small to heavy load applications. The linear actuators, e.g., a hydraulic cylinder, in linear actuator assemblies are used to cause linear movement, typically reciprocating linear movement, in systems such as, e.g., hydraulic systems. Often, one or more linear actuator assemblies are included in the system which can be subject to frequent loads in a harsh working environment, e.g., in the hydraulic systems of industrial machines such as excavators, front-end loaders, and cranes. Thus, it is strongly desirable that these linear actuator assemblies be durable and reliably function even in a harsh working environment.
However, in a conventional machine, the actuators components are provided separately and usually include numerous parts such as a hydraulic cylinder, a hydraulic pump, a motor, a fluid reservoir and appropriate valves that must be connected. The motor drives the hydraulic pump to provide pressurized fluid from the fluid reservoir to the hydraulic cylinder in a predetermined manner, which in turn causes the piston rod of the cylinder to move within the body of the cylinder. When the hydraulic cylinder is retracted, extra fluid is sent back to the fluid reservoir. To control the flow in the hydraulic system, the hydraulic pump can be a variable-displacement hydraulic pump and/or a directional flow control valve (or another type of flow control device) can be included in the system. In these types of systems, the motor that drives the operation of the hydraulic pump is often run at constant speed and the directional flow control valve, for example, can provide the appropriate porting to the hydraulic cylinder to extend or retract the hydraulic cylinder. Typically, the motor and hydraulic pump are run at a high speed, which builds up temperature in the hydraulic fluid. Thus, the reservoir also acts to keep the average fluid temperature down by increasing the fluid volume in the system. However, these hydraulic systems can be relatively large and complex. In addition, the various components are often located spaced apart from one another. To interconnect these parts, various additional components like connecting shafts, hoses, pipes, and/or fittings are used in a complicated manner. Moreover, these components are susceptible to damage or degradation in harsh working environments, thereby causing increased machine downtime and reduced reliability of the machine. In addition, when a hydraulic pump fails because its motor has failed, there may be no safe way to shut down the system or to operate the system until the current operation has completed.
Further limitation and disadvantages of conventional, traditional, and proposed approaches will become apparent to one skilled in the art, through comparison of such approaches with embodiments of the present invention as set forth in the remainder of the present disclosure with reference to the drawings.